Efficient and Private Three-Party Publish/Subscribe

We consider the problem of modeling and designing publish/subscribe protocols that safeguard the privacy of clients’ subscriptions and of servers’ publications while guaranteeing efficient latency in challenging scenarios (i.e., real-time publication, high data arrival rate, etc.). As general solutions from the theory of secure function evaluation protocols would not achieve satisfactory performance in these scenarios, we enrich the model with a third party (e.g., a cloud server). Our main result is a three-party publish/subscribe protocol suitable for practical applications in such scenarios because the publication phase uses only symmetric cryptography operations (a result believed not possible without the third party). At the cost of only a very small amount of privacy loss to the third party, and with no privacy loss to the publishing server or the clients, our protocol has very small publication latency, which we measured for large parameter ranges to be just a small constant factor worse than a publish/subscribe protocol guaranteeing no privacy.